Thrust Bearing Pad Having Metallic Substrate

ABSTRACT

A thrust bearing pad includes a relatively low wear and low friction contact layer disposed on a metallic substrate. The metallic substrate allows a manufacturer to couple the thrust bearing pad to a corresponding metallic thrust bearing in a relatively secure manner while the contact layer extends the operating life of the thrust bearing and minimizes maintenance.

RELATED APPLICATIONS

This patent application is a continuation of U.S. Utility applicationSer. No. 14/102,657, filed on Dec. 11, 2013, entitled “Thrust BearingPad Having Metallic Substrate” which claims the benefit of U.S.Provisional Application No. 61/735,767, filed on Dec. 11, 2012, entitled“Thrust Bearing Pad Having Metallic Substrate,” the contents andteachings of each of which are hereby incorporated by reference in theirentirety.

BACKGROUND

In conventional drilling systems, such as indicated in FIG. 1A, a thrustbearing 10 is installed at the end face 12 of a rotating shaft 14 tosubstantially maintain the shaft in a given position within a housing 13and relative to a longitudinal axis 15 of the drilling system. Forexample, the thrust bearing 10 opposes an axial load 16 generated by theshaft 14 during operation to maintain the longitudinal positioning ofthe shaft. The axial or thrust load 16 can be relatively high for mudpumps, such as used in drilling for the oil and gas industry, and forother rotating equipment, such as large gas and steam turbines as wellas blowers, for example.

SUMMARY

As the face of the shaft 14 rotates against the thrust bearing 10, atypical thrust bearing 10 includes a set of thrust pads 20 mounted to adisk 22, as illustrated in FIG. 1B. Certain conventional thrust pads 20are manufactured from a special polymeric or metallic material, such aspolyether ether ketone (PEEK) or bronze. However, during operation underextreme loading conditions, such as under millions of pounds of axialload, the thrust pads 20 can wear away from the disk 22 relativelyquickly, thereby limiting the operating life of the thrust bearing 10and requiring frequent maintenance. Other conventional thrust pads 20are manufactured from polycrystalline diamond material and are typicallyutilized in extreme loading applications. However, polycrystallinediamond thrust pads are relatively expensive and impractical forconventional applications.

By contrast to conventional thrust pads, embodiments of the presentinnovation relate to a thrust bearing pad having a relatively low wearand low friction contact layer disposed on a metallic substrate. Themetallic substrate allows a manufacturer to couple the thrust bearingpad to a corresponding metallic thrust bearing in a relatively securemanner while the contact layer extends the operating life of the thrustbearing and minimizes maintenance.

In one arrangement, the contact layer is manufactured from a ceramic padthat is brazed to a metallic substrate. In one arrangement, the contactlayer is configured as a monolithic ceramic material brazed to themetallic substrate. In one arrangement, the contact layer is configuredas a cermet material applied to the metallic substrate. In onearrangement, the contact layer is configured as a relatively hardmetallic layer. The ceramic, cermet, or relatively hard metallic layerscan each include a hard diamond-like carbon (DLC) type coating disposedthereon. In one arrangement, the contact layer is a plastic materialhaving an interlocking structure, such as a dovetail channel, configuredto mate with a corresponding interlocking structure of the metallicsubstrate.

The resulting thrust bearing pads are cost effective yet provide highperformance relative to conventional thrust pads. In addition to lowwear characteristics, the thrust bearing pads are configured with arelatively low coefficient of friction. Accordingly, during operationwhen running against a rotating, metallic shaft, the thrust bearing padscan reduce heat generation to minimize damage to the shaft and thrustbearing.

In one arrangement, a thrust bearing pad includes a metallic substrateconfigured to be coupled to a carrier element and a ceramic pad brazedto the metallic substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages will beapparent from the following description of particular embodiments of theinnovation, as illustrated in the accompanying drawings in which likereference characters refer to the same parts throughout the differentviews. The drawings are not necessarily to scale, emphasis instead beingplaced upon illustrating the principles of various embodiments of theinnovation.

FIG. 1A illustrates a schematic representation of a prior art shafthaving a thrust bearing.

FIG. 1B illustrates a schematic representation of a prior art set ofthrust pads of the thrust bearing of FIG. 1A.

FIG. 2A illustrates a side view of a schematic representation of athrust bearing having a set of thrust bearing pads, according to onearrangement.

FIG. 2B illustrates a side view of a contact layer of a thrust bearingpad having a monolithic ceramic layer and a DLC coating layer, accordingto one arrangement.

FIG. 2C illustrates a top view of a schematic representation of a thrustbearing having a set of thrust bearing pads, according to onearrangement.

FIG. 3A illustrates a brazed joint configuration between a monolithicceramic layer and a metallic base configured as a metallic cup,according to one arrangement.

FIG. 3B illustrates an exploded view of a brazed joint configurationbetween a monolithic ceramic layer and a metallic base using asubstantially continuous butt joint with a soft metal interlayer,according to one arrangement.

FIG. 3C illustrates an assembled brazed joint configuration between amonolithic ceramic layer and a metallic base using a substantiallycontinuous butt joint with a soft metal interlayer, according to onearrangement.

FIG. 3D illustrates a brazed joint configuration between a monolithicceramic layer and a metallic base using an interrupted butt joint with asoft metal interlayer, according to one arrangement.

FIG. 4 illustrates a schematic representation illustration of a thrustbearing pad having a cermet layer and a metallic base layer, accordingto one arrangement.

FIG. 5A illustrates a prior art molded plastic pad over a metallic baselayer.

FIG. 5B illustrates a thrust bearing pad having a plastic layerconfigured with an interlocking structure that mates with a metallicbase layer, according to one arrangement.

FIG. 6A illustrates a set of thrust bearing pads having alternatingshallow concave and convex geometries configured to define a relativelywavy surface, according to one arrangement.

FIG. 6B illustrates a trapezoidal thrust bearing pad defining arelatively shallow radial groove, according to one arrangement.

FIG. 7 is a schematic illustration showing hydrodynamic pressure buildup in the shallow radial groove of FIG. 6B, according to onearrangement.

DETAILED DESCRIPTION

FIG. 2A illustrates a schematic representation of a thrust bearing 40having a set of thrust bearing pads 42 disposed on a carrier element orcarrier disc 44, according to one arrangement. Each thrust bearing pad42 includes a contact layer 46 configured to contact a rotating shaftand a metallic substrate 48 configured to secure the thrust bearing pad42 to the carrier disc 44. While the metallic substrate 48 can bemanufactured from a variety of materials, in one arrangement, themetallic substrate 48 is manufactured from a corrosion resistantmaterial, such as stainless steel materials. While the thrust bearingpads 42 can be secured to the carrier disc 44 in a variety of ways, inone arrangement, the metallic substrates 48 of the thrust bearing pads42 are bolted to the carrier disc 44. Alternately, the metallicsubstrates 48 of thrust bearing pads 42 can be secured to the carrierdisc 44 to allow tilting of the pads 42 in the direction of rotationduring operation.

As indicated above, the contact layer 46 is disposed on the metallicsubstrate 48 and is manufactured from a relatively low wear and lowfriction material. As described below, the contact layer 46, metallicsubstrate 48, and resulting thrust bearing pad 42 can be configured in avariety of ways.

In one arrangement, with reference to FIGS. 2B through 3C, the thrustbearing pad 142 is configured as a ceramic disc or pad 146 brazed to ametal substrate 148. For example, the ceramic pad 146, as illustrated inFIG. 2B, can be a monolithic ceramic material, such as silicon carbide(e.g., both sintered and reaction bonded or a composite of siliconcarbide and other ceramics such as aluminum oxide), silicon nitride(e.g., both sintered and reaction bonded or a composite of siliconnitride and other ceramics such as aluminum oxide), aluminum oxide mixedwith zirconium oxide, or transformation toughened zirconium oxide.Additionally, the ceramic pad 146 can be manufactured from othermonolithic carbides, nitrides, and oxide ceramics having superior lowfriction and low wear characteristics relative to conventional pads. Forexample, a coefficient of friction in the range of between about 0.1 and0.3 is considered low. Conventionally, the coefficient of friction ofplastic to metal is within this range. However, the corresponding wearrate of plastic to metal is high. Typically, plastic thrust bearing padsutilized in a mud pump wear off within 8 and 24 hrs of operation. Bycontrast, interaction between the ceramic layer 146 and a metallicrotating shaft simultaneously provides a relatively low coefficient offriction (e.g., between about 0.1 and 0.3) and a relatively low wearrate.

In one arrangement, to further enhance the relatively low wear and lowfriction characteristics of the ceramic pad 146, these monolithicceramics can be coated with a diamond like carbon (DLC) coating 150,such as on a bearing or contact surface of the ceramic pad 146.Typically, DLC coatings are formed of a carbon material having anamorphous, non-crystalline carbon structure, such as produced through achemical vapor deposition or sputter deposition process using a graphitetarget. DLC coatings have relatively high hardness values, in a range ofabout 3400 and about 4800 Knoop hardness (HK) Additionally, DLC coatingshave relatively low coefficient of friction values, in a range of about0.09 to about 0.15 running against hard metallic surfaces, such as ahigh strength steel rotor.

In one arrangement, the DLC coating 150 is applied using a PhysicalVapor Deposition (PVD) or sputtering process which improves theeffectiveness of the DLC coating 150. If DLC is applied directly on themetallic substrate 148, which can deform under a relatively high contactload, the thin hard and brittle DLC coating layer 150 will also deformwith the metallic substrate 148 and can fracture. Such fracture cancreate fragments that become lodged between the thrust bearing and theend face of the rotating shaft, thereby resulting in three body wear ofthe shaft and cause serious damage. Accordingly, application of the DLCcoating 150 over the ceramic pad 146 minimizes such cracking andgeneration of fragments.

As indicated in FIGS. 3A through 3D, the ceramic layer 146 is secured tothe metal substrate 148. Monolithic ceramic materials have a relativelylower coefficient of thermal expansion compared to that of thecorresponding metallic substrates. For example, thermal expansioncoefficients for ceramic materials are between about 3×10⁻⁶ and 5×10⁻⁶per ° C. whereas thermal expansion coefficients for metallic alloys arebetween about 10×10⁻⁶ and 15×10⁻⁶ per ° C. In one arrangement, toaccount for the difference in thermal expansion coefficients, to providea relatively high joint strength, and to limit or prevent cracking ofthe relatively brittle ceramic layer 146, a manufacturer brazes theceramic layer 146 to the metal substrate 148. A variety of brazingprocesses can be used to attach the ceramic layer or pad 146 to themetallic substrate 148, as will be described in detail below.

One brazing process, such as illustrated in FIG. 3A, couples acircumferential surface of the ceramic disc or pad 146 disposed within ametallic base or cup 149. During the brazing process, a circumferentialsurface of the ceramic pad 146 is first metalized 152. Conventionalmetalization processes use a Mo—Mn slurry, which is applied on theceramic part and fired in a reducing atmosphere. The process forms aMo—Mn layer chemically bonded to ceramics. As an alternate to theconventional Mo—Mn process, a manufacturer can apply a relatively thinnickel-base, copper-silver base, silver-base and/or similar braze alloypaste with active metals such as titanium around the circumference ofthe ceramic pad 146 and run the ceramic pad 146 through a braze cycle.The braze paste reacts with the ceramic pad 146 and forms a thinmetalized braze alloy layer 152 chemically bonded to the ceramic pad146. Because the metallic braze alloy layer 152 is relatively thin, itdoes not cause damage to the ceramic face during cooling, which stemsfrom stresses generated by a thermal expansion coefficient mismatchbetween the braze alloy layer 152 and the pad 146.

Following the metallization process, the metalized braze alloy layer 152of the ceramic pad 146 is brazed directly to the metallic base 149. Inone arrangement, the first metalizing braze alloy 152 should have ahigher brazing temperature compared to the second braze alloy 158 usedfor joining the metalized ceramic pad 146 and the metallic base 149. Forexample, a SiC ceramic pad 146 can be metalized with a nickel basebrazing alloy, such as BNi-2, at a brazing temperature of about 1000° C.The metallization process is followed by brazing the braze alloy layer152 of the SiC ceramic pad 146 to an inner surface of the metallic cup149 with a soft Ag—Cu braze alloy 158 at a brazing temperature of about850° C. The two step brazing process is known as step brazing.

In one arrangement, a radial clearance or joint gap (G) between theceramic pad 146 and the inner surface the metallic cup 149 is betweenabout 0.0005 inches and 0.01 inches and can be more specifically betweenabout 0.001 inches and 0.004 inches. For example, the radial clearance Gis configured as the total thickness of a braze joint 158, such as aAg—Cu braze joint, disposed within the annular space between the outerdiameter of the braze alloy layer 152 and the inner diameter of themetallic cup 149. The size of the radial clearance G is selected basedupon the physical properties of the ceramic pad 146, the braze joint158, and the metalized layer or braze alloy layer 152. A relativelylarger radial clearance G can cause the ceramic pad 146 to crack becauseof a relatively high compressive stress generated by a thickercircumferential braze alloy ring. By contrast, a relatively smaller gapis difficult to maintain.

In one arrangement, a rim of the metallic cup 149 is beveled to holdadditional braze paste to fill the larger gap created by higher thermalexpansion of the metallic cup 149 at the brazing temperature. If thejoint between the ceramic pad 146 and an inner diameter the metallic cup149 is too thick, the annular braze joint 158 can impart enoughcompressive force during solidification of the braze alloy to crack theceramic pad 146 even if the braze alloy is relatively soft, such asAg—Cu.

In one arrangement, the area of metallization 152 is also important. Forexample, the metalized area 152 extends substantially up to the cup rim154 of the metallic cup 149 to minimize spreading of the braze alloycould spread beyond the joint (i.e., beyond the cup rim 154) and tomaintain the strength of the bond between the ceramic pad 146 and themetallic cup 149 at the cup rim 154. By contrast, if the braze alloylayer 152 were to extend beyond the partial length PL, such as along alength L of the ceramic pad 146, during the brazing process, the brazealloy could spread beyond the joint between the ceramic pad 146 and themetallic cup 149, leaving the joint porous and weak.

In one arrangement, the metallic cup 149 defines a clearance 156 at thebottom corner relative to the ceramic pad 146. For example, theclearance 156 extends about an inner periphery of the metallic cup 149.The clearance 156 is configured to minimize or limit any contact betweenthe ceramic pad corners and the metallic cup 149 to limit or eliminatelocalized stress raisers at the ceramic pad corners. This joint designis configured to impart compressive stress on the ceramic pad 146 whichis beneficial as ceramics typically cannot withstand tensile stresses.

In another brazing process, as illustrated in FIGS. 3B and 3C, amanufacturer forms a butt joint 160 with a substantially continuousinterface between the ceramic pad 146 and the metallic substrate 148.Use of the butt joint 160 maximizes the contact area of the thrustbearing pads 142 and the rotating shaft by eliminating the relativelylager foot print of the metallic cup 148, illustrated in FIG. 3A. Duringthe brazing process, as indicated in FIG. 3B, a brazing interface 162 ofthe ceramic pad 146 is metalized first. For example, a metallic brazealloy layer 152 is formed about the outer periphery and the base of theceramic layer 146. A thin foil of a soft metal 164, such as Cu, is theninserted between the base of the ceramic pad 146 and a support surfaceof a disc-shaped metallic base 168. A first layer of soft braze alloypaste 165, such as Ag—Cu, is applied on the support surface of themetallic base 168, followed by placement of the Cu foil 164 over thefirst paste layer 165, and placement of a second layer of soft brazealloy paste 167 (e.g., the same braze paste used for the first layer165) on top of the Cu foil 164. The ceramic pad 146 is then disposed onthe paste-coated foil 164. The assembly is brazed with a dead weight tohold all the components together during brazing to create the finalthrust bearing pad 142, such as illustrated in FIG. 3C.

In another brazing process, as illustrated in FIG. 3D, a manufacturerforms a butt joint 170 between ceramic pad 146 and the metallicsubstrate 178 with an interrupted interface prior to brazing the ceramicpad 146 and the metallic substrate 148. For example, the metallicsubstrate 178 is interrupted by a set of channels 172 disposed betweenthe metallic substrate and the ceramic pad 146. In one arrangement, themetallic substrate 178 is configured with relatively thin vertical fins175 disposed on either side of each channel 172 and which can minimizejoint stress by making the interface more compliant. For example, withthe vertical fins 175 configured as relatively thin structures, thevertical fins 175 can bend to accommodate stresses resulting from athermal coefficient mismatch between the ceramic pad 146 and themetallic substrate 178. The interrupted butt joint generates less stressbetween the ceramic pad 146 and the metallic substrate 178, such ascaused by a mismatch in the thermal expansion coefficients.Additionally, the vertical fins 175 include braze joints 167 disposedsubstantially at a top surface 177 of each fin 175. Accordingly, thebraze joints 167 are separated by the channels 172 thereby making thebraze joints 167 discontinuous to reduce stress at the interface betweenthe ceramic pad 146 and the metallic substrate 178.

For the brazing methods described above, in one arrangement, the brazealloy is configured as a relatively soft and ductile material, such asAg—Cu and/or pure Ag based braze alloys. With such a configuration,following the brazing process and during cooling of the thrust bearingpad 142 from the braze temperature, the relatively soft braze alloy isconfigured to plastically deform which diffuses stress between theceramic pad 146 and the metallic substrate 148. In addition, therelatively soft transition layer, such as the Cu foil described withrespect to FIGS. 3B and 3D, can undergo plastic deformation duringcooling to diffuse stresses generated due thermal expansion mismatch.

In another arrangement, in order to minimize stresses within the ceramicpad 146, multiple layers of materials can be deposited between theceramic pad 146 and the metallic substrate 148 where the layers providea gradual change in the thermal expansion coefficient. While thematerials can be applied in a variety of way, in one arrangement, amanufacturer utilizes a PVD process to deposit various layers on theceramic pad. For example, the ceramic pad 146 can be coated with ametallic sputter deposited layer, such as tungsten, having a low thermalexpansion coefficient such as between about 4×10⁻⁶ per ° C. and 5×10⁻⁶per ° C. This layer, in turn, can be coated with materials havingsubsequent layers of increasingly higher expansion coefficients, such asmaterials having a thermal expansion coefficient between about 6×10⁻⁶per ° C. and 18×10⁻⁶ per ° C., until the thermal expansion coefficientof the last layer matches the expansion coefficient of the metallicsubstrate 148.

In one arrangement, with reference to FIG. 4, a thrust bearing pad 242includes a composite ceramic and metal binder material, or cermet, layer246 brazed to a metal substrate 248. For example, the cermet layer 246can be manufactured from WC—Co, WC—Cr—Co, WC—Cr—Ni, Cr2C3-Cr—Ni,Al2O3-binder, Ni and Co base Tribaloys, and other cermets. The cermetlayer 246 is configured to increase the fracture toughness of the thrustbearing pad 242, as well as reduce the coefficient of frictionassociated with the metal substrate 248. For example, fracture toughnessof monolithic ceramics is between about 3 and 10 MPa-m^(−0.5) whereasfracture toughness of high strength steels is between about 30 and 90MPa-m^(−0.5). For cermets, fracture toughness values will be in betweenthese two ranges based on the relative volume fractions of the ceramicand the metallic binder.

The cermet layer 246 can be applied to the metallic substrate 248 usinga variety of techniques, such as by thermal spray, sintering of ceramicand metal powder, or by a ceramic/metal injection molding (MIM) process.For example, WC—Cr—Ni cermet can be applied on a metallic substrate 248by a thermal spray process such as High Velocity Oxy Fuel (HVOF). Duringapplication, a mixture of WC and Ni—Cr alloy powder particles areinjected into a supersonic oxygen and fuel gas stream. Fuel is ignitedto create melted and semi-melted ceramic and metal powder droplets whichimpinge on the metallic substrate 248 creating a cermet layer 246, asshown in FIG. 4. The cermet layer 246 can also be formed by electrodeposition of a metal ceramic composite coating onto the metallicsubstrate 248. The cermet layer 246 can also be deposited by Ni, Co, Febase and similar hardfacing alloys. For example, the cermet layer 24 canbe applied with a plasma transfer arc process. In another example, thecermet layer 246 can be created by applying a hardfacing alloy powderwith an organic binder to the metallic substrate 248 and by heating thecoated metallic substrate 248 up to the melting point of the hardfacingalloy.

In one arrangement, the cermet layer 246 includes a DLC coating layer250 to reduce both the coefficient of friction and wear associated withthe cermet layer 246.

In one arrangement, a thrust bearing pad is configured as a relativelyhard metallic layer disposed over a metallic substrate (not shown). Withsuch a configuration, the thrust bearing pad has an increased toughnessrelative to conventional thrust pads to better withstand shock, load,and vibration during operation. The relatively hard metallic layer canbe an electroplated hard chrome layer, electroplated Ni, Co and W alloyswith ceramic particles, an electro composite layer, or thermal sprayedCo—Mo—Cr and Ni—Mo—Cr Tribaloys. While the relatively hard metalliclayer can have a variety of hardness values, in one arrangement, thehard metallic layer can have a hardness range of between about 600 and1000 Vicker's Hardness Number (VHN). By comparison, high strength steelshave a hardness range of between about 400 and 600 VHN. During theapplication process, thermal spray is utilized to attach Tribaloy to themetallic substrate and an electrolytic process is utilized to attach anelectrocomposite (e.g., Ni—Co—P—SiC) to the metallic substrate. In onearrangement, the relatively hard metallic layer has a thickness ofbetween about 0.005 inches and 0.01 inches. In one arrangement, a DLClayer can be applied to the relatively hard metallic layer to reduceboth the coefficient of friction and wear associated with the hardmetallic layer.

In one arrangement, plastic materials can also be used with a metallicsubstrate to produce a thrust pad.

With reference to FIG. 5A, a conventional plastic/metal composite thrustpad 500 is shown. During the assembly process, small bronze balls 502are first brazed to a stainless steel base 504 to produce a roughsurface. Various grades of engineered plastics 506 are then molded onthe steel base 504 to create a mechanically interlocking structure whichprovides good mechanical bond between the plastic pad 506 and themetallic base 504. The bronze balls 502 also provide a conductive pathof heat transfer to remove frictional heat generated at the thrust padand rotating shaft end interface. To promote heat transfer, plastics aregenerally filled with copper powder.

By contrast, in one arrangement and with reference to FIG. 5B, a thrustbearing pad 342 includes a plastic layer 344 having a first interlockingstructure 346, such as a dovetail channel, configured to mate with acorresponding second interlocking structure 347 of the metallicsubstrate 348. The thrust bearing pad 342 eliminates the brazing stepdescribed with respect to FIG. 5A. The thrust bearing pad 342simultaneously enhances heat transfer by replacing the above-referencedstainless steel base 504 and brazed bronze spheres 502 with a bronzebase 348 having machined dovetail cross section channels. The thrustbearing pad 342 is more cost effective, provides superior heat transfer,and provides superior joint strength between the plastic pad 344 and themetallic base 348, relative to the conventional thrust pad 500.

With reference to FIG. 2A, each of the thrust bearing pads 42 can beconfigured with a variety of shapes to maximize the load bearing areabetween the thrust bearing 40 and a rotating shaft and to reduce contactpressure on each thrust bearing pad 42. For example, each of the thrustbearing pads 42 can be configured in a generally trapezoidal shape, asillustrated in FIG. 6A, or in a generally circular shape, as illustratedin FIG. 2C.

In one arrangement, to mitigate the relatively high contact pressurefound between the thrust bearing pads 42 and a conventional rotatingshaft, the thrust bearing pads 42 are configured with a hydrodynamiclift-off mechanism. For example, with continued reference to FIG. 6A,the hydrodynamic lift-off mechanism 600 is defined by the set of thrustbearing pads 42. As illustrated, first and third thrust bearing pads42-1 and 42-3 define relatively shallow concave surfaces and the secondthrust bearing pad 42-2 defines a relatively shallow convex surface. Thealternating concave and convex surfaces defines, as the hydrodynamiclift-off mechanism 600, a relatively wavy contact face for the thrustbearing 40. In another example, and with reference to FIG. 6B, thethrust bearing pad 42 defines, as the hydrodynamic lift-off mechanism600, a relatively shallow radial groove 604.

During operation, the hydrodynamic lift-off mechanism 600, as shown ineither FIG. 6A or 6B, forms a converging wedge of fluid (e.g., bearingoil) between the rubbing surfaces of the thrust bearing (e.g., thebearing surface of the contact layer) and the rotating shaft to decreasethe fluid flow cross sectional area and to build up pressure, as shownin FIG. 7, which tries to separate the two rubbing faces. For both thedesigns in FIG. 6A or 6B, the moving shaft surface drags the viscousfluid into a converging gap between the shaft end face and thrustbearing pad 42 with the shallow groove creating an opening pressureprofile. The pressure mitigates contact pressure between the shaft endface and the thrust pad.

While various embodiments of the innovation have been particularly shownand described, it will be understood by those skilled in the art thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the innovation as defined by theappended claims.

What is claimed is:
 1. A thrust bearing pad, comprising: a metallicsubstrate configured to be coupled to a carrier element; and a ceramicpad brazed to the metallic substrate; wherein: the metallic substrate isconfigured as a metallic base; and the ceramic pad comprises a metalizedlayer disposed on at least a base of the ceramic pad, the metalizedlayer coupled to a support surface of the metallic base.
 2. The thrustbearing pad of claim 1, wherein the ceramic pad comprises a monolithicceramic material.
 3. The thrust bearing pad of claim 2, furthercomprising a diamond-like carbon coating disposed on a bearing face ofthe ceramic pad.
 4. The thrust bearing pad of claim 1, wherein theceramic pad comprises a monolithic cermet material.
 5. The thrustbearing pad of claim 4, further comprising a diamond-like carbon coatingdisposed on a bearing face of the ceramic pad.
 6. The thrust bearing padof claim 1, wherein a bearing face of the ceramic pad comprises ahydrodynamic lift-off mechanism.
 7. The thrust bearing pad of claim 6,wherein the hydrodynamic lift-off mechanism comprises at least one of aconvex geometry and a concave geometry defined by the bearing face ofthe ceramic pad.
 8. The thrust bearing pad of claim 6, wherein thehydrodynamic lift-off mechanism comprises a radial groove defined by thebearing face of the ceramic pad.
 9. The thrust bearing pad of claim 6,wherein the thrust bearing pad is configured with a trapezoidal shape.10. The thrust bearing pad of claim 6, wherein the metallic substrate isconfigured to be rotationally secured to the carrier element to allowtilting of the thrust bearing pad relative to the carrier element.
 11. Athrust bearing, comprising: a carrier element; and a set of thrustbearing pads mounted to the carrier element, at least one thrust bearingpad of the set of thrust bearing pads comprising: a metallic substratecoupled to the carrier element; and a ceramic pad brazed to the metallicsubstrate; wherein: the metallic substrate is configured as a metallicbase; and the ceramic pad comprises a metalized layer disposed on atleast a base of the ceramic pad, the metalized layer coupled to asupport surface of the metallic base.
 12. The thrust bearing of claim11, wherein the ceramic pad comprises a monolithic ceramic material. 13.The thrust bearing of claim 12, further comprising a diamond-like carboncoating disposed on a bearing face of the ceramic pad.
 14. The thrustbearing of claim 11, wherein the ceramic pad comprises a monolithiccermet material.
 15. The thrust bearing of claim 14, further comprisinga diamond-like carbon coating disposed on a bearing face of the ceramicpad.
 16. The thrust bearing of claim 11, wherein a bearing face of theceramic pad comprises a hydrodynamic lift-off mechanism.
 17. The thrustbearing of claim 16, wherein the hydrodynamic lift-off mechanismcomprises at least one of a convex geometry and a concave geometrydefined by the bearing face of the ceramic pad.
 18. The thrust bearingof claim 16, wherein the hydrodynamic lift-off mechanism comprises aradial groove defined by the bearing face of the ceramic pad.
 19. Thethrust bearing of claim 16, wherein the thrust bearing pad is configuredwith a trapezoidal shape.
 20. The thrust bearing pad of claim 16,wherein the metallic substrate is configured to be rotationally securedto the carrier element to allow tilting of the thrust bearing padrelative to the carrier element.